1. Field of the Invention
The present invention relates to a traction control apparatus and method for vehicles, which restrains an acceleration slip at wheels.
2. Related Background Art
There are practical traction control systems intended for efficiently yielding traction by restraining the acceleration slip at the wheels mounted on vehicles. An example of such known traction control systems is one as described in Japanese Patent Application Laid-Open No. 5-58264. The traction control system is constructed to detect slip states (for example, slip rates or the like) of the wheels and exert braking force according to the slip states on the wheels, so as to restrain the acceleration slip and maintain frictional force between wheels and road surface, thereby efficiently yielding the traction.
There are also cases wherein the traction control apparatus is designed to control the driving force generated by an engine and transmitted to driven wheels instead of the braking force. In some of these cases, the traction control apparatus is constructed to detect the slip states of the wheels and decrease the driving force transmitted to the wheels in accordance with the slip states, so as to restrain the acceleration slip and maintain the frictional force between wheels and road surface, thereby efficiently producing the traction. In certain cases both the acceleration-slip prevention by the braking force control and the acceleration-slip prevention by the driving force reduction as described above are used in combination. In such traction control, increase amounts of the braking force and/or decrease amounts of the driving force described above become larger as the slip states of the wheels become more prominent (for example, as the slip rates increase).